Cellulose ethers comprising a hydrophobic substituent and/or a cationic substituent have been known since many years.
U.S. Pat. No. 3,472,840 discloses quaternary nitrogen-containing cellulose ethers and their use as flocculents for paper pulp, coal dust or silica or clay or as a retention aid in the manufacture of paper.
U.S. Pat. No. 4,663,159 discloses hydrophobically substituted water-soluble cationic polysaccharides. The hydrophobic substituent is a quaternary substituent which contains nitrogen and an alkyl group of at least 8 carbon atoms. The water-soluble polysaccharides are typically hydroxyethyl celluloses which have on the average about 2 moles of hydroxyethyl substituent per mole of polysaccharide repeat unit. The disclosed hydroxyethyl celluloses have a molecular weight to provide a 2 weight percent Brookfield viscosity between 20 and 500 cps, which corresponds to about 400-1,600 anhydroglucose repeat units. The hydrophobically substituted water-soluble polysaccharides are useful in hair and skin treatment formulations, such as shampoos and hand lotions. However, it would be desirable to improve the substantivity of these polymers, that means the retention of the polymers at a solid surface, such as hair or skin, when aqueous compositions containing such polymers, are applied to hair or skin.
U.S. Pat. No. 5,407,919 discloses double substituted cationic cellulose ethers substituted with greater than 0.11 to 0.25 moles, per mole of anhydroglucose unit, of a hydrophobic substituent and with from 0.05 to 0.50 moles, per mole of anhydroglucose unit, of a cationic substituent. The cationic cellulose ethers have enhanced viscosity and foaming, but poor substantivity. Unfortunately, typical shampoo formulations containing these cationic cellulose ethers are very viscous, to the point of forming gels, which makes them impractical.
Accordingly, it would be desirable to provide new cellulose ethers which are useful in personal care compositions, such as hair or skin care compositions. It would be particularly desirable to provide new cellulose ethers which provide hair or skin care compositions with an optimized viscosity and/or good substantivity. It is a preferred object of the present invention to provide new cellulose ethers which are useful for preparing hair care compositions with good wet and dry combability and/or a good wet and dry feel. It is another preferred object of the present invention to provide new cellulose ether derivatives for preparing skin care compositions which comprise a moisturizing agent, particularly for preparing skin care compositions which leave a high level of moisturizing agent, such as sunflower seed oil on the skin.